<!DOCTYPE HTML>
<html>
<!--
https://bugzilla.mozilla.org/show_bug.cgi?id=1304689
-->
<head>
  <meta charset="utf-8">
  <title>Test for Bug 1285070</title>
  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
  <script type="application/javascript" src="/tests/SimpleTest/paint_listener.js"></script>
  <script type="application/javascript" src="apz_test_utils.js"></script>
  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
  <style type="text/css">
    #outer {
        height: 400px;
        width: 415px;
        overflow: scroll;
        position: relative;
        scroll-behavior: smooth;
    }
    #outer.contentBefore::before {
        top: 0;
        content: '';
        display: block;
        height: 2px;
        position: absolute;
        width: 100%;
        z-index: 99;
    }
  </style>
  <script type="application/javascript">

function* test(testDriver) {
  var utils = SpecialPowers.DOMWindowUtils;
  var elm = document.getElementById('outer');

  // Set margins on the element, to ensure it is layerized
  utils.setDisplayPortMarginsForElement(0, 0, 0, 0, elm, /*priority*/ 1);
  yield waitForAllPaints(function() {
    flushApzRepaints(testDriver);
  });

  // Take control of the refresh driver
  utils.advanceTimeAndRefresh(0);

  // Start a smooth-scroll animation in the compositor and let it go a few
  // frames, so that there is some "user scrolling" going on (per the comment
  // in AsyncPanZoomController::NotifyLayersUpdated)
  elm.scrollTop = 10;
  utils.advanceTimeAndRefresh(16);
  utils.advanceTimeAndRefresh(16);
  utils.advanceTimeAndRefresh(16);
  utils.advanceTimeAndRefresh(16);

  // Do another scroll update but also do a frame reconstruction within the same
  // tick of the refresh driver.
  elm.scrollTop = 100;
  elm.classList.add('contentBefore');

  // Now let everything settle and all the animations run out
  for (var i = 0; i < 60; i++) {
    utils.advanceTimeAndRefresh(16);
  }
  utils.restoreNormalRefresh();

  yield flushApzRepaints(testDriver);
  is(elm.scrollTop, 100, "The scrollTop now should be y=100");
}

if (isApzEnabled()) {
  SimpleTest.waitForExplicitFinish();
  pushPrefs([["apz.displayport_expiry_ms", 0]])
  .then(waitUntilApzStable)
  .then(runContinuation(test))
  .then(SimpleTest.finish);
}

  </script>
</head>
<body>
 <div id="outer">
  <div id="inner">
    this is some scrollable text.<br>
    this is a second line to make the scrolling more obvious.<br>
    and a third for good measure.<br>
    this is some scrollable text.<br>
    this is a second line to make the scrolling more obvious.<br>
    and a third for good measure.<br>
    this is some scrollable text.<br>
    this is a second line to make the scrolling more obvious.<br>
    and a third for good measure.<br>
    this is some scrollable text.<br>
    this is a second line to make the scrolling more obvious.<br>
    and a third for good measure.<br>
    this is some scrollable text.<br>
    this is a second line to make the scrolling more obvious.<br>
    and a third for good measure.<br>
    this is some scrollable text.<br>
    this is a second line to make the scrolling more obvious.<br>
    and a third for good measure.<br>
    this is some scrollable text.<br>
    this is a second line to make the scrolling more obvious.<br>
    and a third for good measure.<br>
    this is some scrollable text.<br>
    this is a second line to make the scrolling more obvious.<br>
    and a third for good measure.<br>
    this is some scrollable text.<br>
    this is a second line to make the scrolling more obvious.<br>
    and a third for good measure.<br>
    this is some scrollable text.<br>
    this is a second line to make the scrolling more obvious.<br>
    and a third for good measure.<br>
    this is some scrollable text.<br>
    this is a second line to make the scrolling more obvious.<br>
    and a third for good measure.<br>
    this is some scrollable text.<br>
    this is a second line to make the scrolling more obvious.<br>
    and a third for good measure.<br>
    this is some scrollable text.<br>
    this is a second line to make the scrolling more obvious.<br>
    and a third for good measure.<br>
    this is some scrollable text.<br>
    this is a second line to make the scrolling more obvious.<br>
    and a third for good measure.<br>
    this is some scrollable text.<br>
    this is a second line to make the scrolling more obvious.<br>
    and a third for good measure.<br>
  </div>
 </div>
</body>
</html>
